Abradable material feedstock and methods and apparatus for manufacture

ABSTRACT

An apparatus for manufacturing a powder has: a chamber; a temperature control system for the chamber interior; and a conveyor within the chamber. First, second, and third powder sources supply respective first, second, and third powders along respective first, second, and third powder flowpaths. The second and third flowpaths merge with the first flowpath along the conveyor. The apparatus comprises a vaporizer for vaporizing a solvent to be delivered to the second and third powders along the second and third powder flowpaths.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. patent application Ser. No.15/223,480, filed Jul. 29, 2016, and entitled “Abradable MaterialFeedstock and Methods and Apparatus for Manufacture”, now U.S. Pat. No.10,315,249, the disclosure of which is incorporated by reference hereinin its entirety as if set forth at length.

BACKGROUND

This disclosure relates to agglomerate powders for thermal spray. Moreparticularly, it relates to such powders for forming gaspath leakageseals for gas turbine engines.

Gas turbine engines, such as those used to power modern commercial andmilitary aircraft, generally include one or more compressor sections topressurize an airflow, a combustor section for burning hydrocarbon fuelin the presence of the pressurized air, and one or more turbine sectionsto extract energy from the resultant combustion gases. The airflow flowsalong a gaspath through the gas turbine engine.

The gas turbine engine includes a plurality of rotors arranged along anaxis of rotation of the gas turbine engine. The rotors are positioned ina case, with the rotors and case having designed clearances between thecase and tips of rotor blades of the rotors. It is desired to maintainthe clearances within a selected range during operation of the gasturbine engine as deviation from the selected range can have a negativeeffect on gas turbine engine performance. For each blade stage, the casetypically includes an outer airseal located in the case immediatelyoutboard (radially) of the blade tips to aid in maintaining theclearances within the selected range.

Within the compressor section(s), temperature typically progressivelyincreases from upstream to downstream along the gaspath. Particularly,in relatively downstream stages, heating of the airseals becomes aproblem. U.S. patent application Ser. No. 14/947,494, of Leslie et al.,entitled “Outer Airseal for Gas Turbine Engine”, and filed Nov. 20, 2015('494 application), the disclosure of which is incorporated by referencein its entirety herein as if set forth at length, discusses severalproblems associated with heat transfer to outer airseals and severalsolutions.

The airseal typically has an abradable coating along its inner diameter(ID) surface. In relatively downstream stages of the compressor wherethe blades have nickel-based superalloy substrates, the abradablecoating material may be applied to a bondcoat along the metallicsubstrate of the outer airseal. For relatively upstream sections wherethe compressor blades comprise titanium-based substrates (a potentialsource of fire) systems have been proposed with a fire-resistant thermalbarrier layer intervening between the bondcoat and the abradablematerial. An example of such a coating is found in U.S. Pat. No.8,777,562 of Strock et al., issued Jul. 15, 2014 and entitled “Blade AirSeal with Integral Barrier”.

Among coating application techniques are thermal spray processes such asair plasma spray. Typically, the plasma spray process involves a singlefeedstock outlet discharging a mixture of coating constituents andfugitive porosity former in to a plasma jet. Proposals have been made tosegregate the porosity former and introduce that through a relativelydownstream outlet while the matrix and solid lubricant are introducedfrom a conventionally located upstream outlet. Examples of these arefound in U.S. Pat. No. 4,696,855, of Petit, Jr. et al., issued Sep. 29,1987, and entitled “Multiple Port Plasma Spray Apparatus and Method forProviding Sprayed Abradable Coatings”, and U.S. Pat. No. 4,299,865, ofClingman et al., issued Nov. 10, 1981 and entitled “Abradable CeramicSeal and Method of Making Same”. U.S. Pat. No. 4,386,112, of Eaton etal., issued May 31, 1983, and entitled “Co-Spray Abrasive Coating” showsseparate introduction of matrix and abrasive in an abrasive coating.

SUMMARY

One aspect of the disclosure involves a method for manufacturing apowder, the method comprising: vaporizing a solvent; passing a metallicpowder and a polymer powder through the solvent vapor to mix themetallic powder with the polymer powder; and removing said solvent.

A further embodiment may additionally and/or alternatively include themetallic powder being a second metallic powder. The method furthercomprises driving a flow of a first metallic powder along a flowpath.The method further comprises introducing the second metallic powder andpolymer powder to the flow of the first metallic powder.

A further embodiment may additionally and/or alternatively includevibratory mixing of the mixed second metallic powder and polymer powderand the first metallic powder to produce a blend.

A further embodiment may additionally and/or alternatively include sizeclassifying the blend.

A further embodiment may additionally and/or alternatively include thesize classifying comprising: feeding back undersize particles to asource of the first metallic powder or the second metallic powder; andcrushing oversize particles and feeding the crushed particles back intoa classifier performing the size classifying.

A further embodiment may additionally and/or alternatively includecontrolling a temperature of the first metallic powder to a firsttemperature; controlling a temperature of the second metallic powder toa second temperature; and controlling a temperature of the polymerpowder to a third temperature.

A further embodiment may additionally and/or alternatively include thefirst temperature being greater than the second temperature and thesecond temperature being greater than the third temperature.

A further embodiment may additionally and/or alternatively include thefirst temperature being equal to or greater than a dew point of thesolvent vapor; the second temperature being equal to or less than thedew point; and the third temperature being less than the dew point.

A further embodiment may additionally and/or alternatively include thecontrolling the temperature of the first metallic powder to the firsttemperature comprising heating; the controlling the temperature of thesecond metallic powder to the second temperature comprising heating; andthe controlling the temperature of the polymer powder to the thirdtemperature comprising cooling.

A further embodiment may additionally and/or alternatively include anoverlapping powder delivery process of the second metallic powder andthe polymer powder providing: the mixing of the second metallic powderand the polymer powder; and the introduction of the mixed secondmetallic powder and polymer powder to the flow of the first metallicpowder.

A further embodiment may additionally and/or alternatively include theoverlapping powder delivery process comprising: delivering the secondmetallic powder onto the flow of the first metallic powder over a firstfootprint; and delivering the polymer powder over a second footprintwithin the first footprint.

A further embodiment may additionally and/or alternatively include theoverlapping powder delivery process comprises overlapping spraying.

A further embodiment may additionally and/or alternatively include thefirst metallic powder and the second metallic powder being of alloys ofthe same composition.

A further embodiment may additionally and/or alternatively includemaintaining the solvent vapor at a partial pressure of at least 50% of achamber atmosphere.

A further embodiment may additionally and/or alternatively includecomprising acetone.

A further embodiment may additionally and/or alternatively includepassing a non-metallic filler through the solvent vapor.

Another aspect of the disclosure involves an apparatus for manufacturinga powder. The apparatus comprises: a chamber; a temperature controlsystem for the chamber interior; a vibratory conveyor within thechamber; a first powder source within or coupled to the chamber; a firstpowder flowpath from the first powder source through the chamber andpassing along the vibratory conveyor; a second powder source within orcoupled to the chamber; a second powder flowpath from the second powdersource merging with the first powder flowpath along the vibratoryconveyor; a third powder source within or coupled to the chamber; athird powder flowpath from the third powder source merging with thefirst powder flowpath along the vibratory conveyor; and a vaporizerwithin the chamber or coupled thereto to deliver vaporized liquid to thechamber.

A further embodiment may additionally and/or alternatively include: aclassifier; and a return flowpath from the classifier to the firstflowpath.

A further embodiment may additionally and/or alternatively include theclassifier being a two-stage classifier with the first stage having anover-size particle flowpath passing back through a crusher.

A further embodiment may additionally and/or alternatively include thetemperature control system comprising a heater.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic view of a powder-producing apparatus.

FIG. 1A is an enlarged view of a classifier of the apparatus of FIG. 1.

FIG. 2 is a schematic sectional view of a first agglomerate.

FIG. 3 is a schematic sectional view of a second agglomerate.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIG. 1 shows an apparatus 20 for producing a feedstock for thermal sprayprocesses. The exemplary feedstock is a powder. The particles of thepowder are, themselves made up of multiple particles of constituentpowders. In one group of embodiments, the constituent powders compriseone or more metallic powders for ultimately forming a matrix of thesprayed material. Additional powders include a fugitive porosity former(“fugitive”) to form porosity in the ultimate coating (e.g., after abake-out or chemical removal) and may include other non-metallic powderssuch as solid lubricants or other fillers to affect friability or otherproperties of the sprayed material.

For example, FIGS. 2 and 3 respectively schematically show atwo-component powder agglomerate particle 200 and a three-componentpowder agglomerate particle 201. Each has a core 202 formed by a singleparticle of the fugitive. A shell 204, 205 is formed of multipleparticles, namely alloy particles 206 in FIG. 2 and a combination ofalloy particles 206 and non-metallic filler particles 208 in FIG. 3.

The agglomerate component particles may be modeled as spheres. If thecore 202 of agglomerate 200 has a diameter D₁ and the alloy particleseach have a diameter D₂, the overall particle may be modeled as having adiameter D=D₂+2D₁. Maximum theoretical coverage of the core surface maynot be achieved in practice. Thus, some fraction of this may be used tocalculate parameters that represent overall by volume alloy content to,in turn, predict overall by volume alloy content in the ultimatecoating. Similar calculations may be performed for the three-componentagglomerate particle 201. A sample calculation calculates the surface ofa sphere of radius R=0.5(D₁+D₂) as 4ΠR². An amount of the alloyparticles may be calculated to cover that area up to a packing limit. Anexemplary modelling models the alloy particles' cross-sectional area ascovering 60% of that sphere surface which is a little less than thehexagonal close packed or square array packing. The table below usesthat 60% figure as a fractional coverage of 0.6.

TABLE I Component Dimensions and Relative Volumes Assumed Fugitive AlloyFractional Volume Volume D1 (μm) D2 (μm) D (μm) coverage FractionFraction 50 22 94 0.60 0.077 0.923 100 22 144 0.60 0.188 0.812 150 22194 0.60 0.282 0.718 50 16 82 0.60 0.157 0.843 100 16 132 0.60 0.3260.674 150 16 182 0.60 0.444 0.556 50 11 72 0.60 0.316 0.684 100 11 1220.60 0.528 0.472 150 11 172 0.60 0.642 0.358 50 9 68 0.60 0.425 0.575100 9 118 0.60 0.634 0.366 150 9 168 0.60 0.733 0.267 50 6 62 0.60 0.6490.351 100 6 112 0.60 0.805 0.195 150 6 162 0.60 0.865 0.135

For a three-component system, a similar approximation may be used.

The apparatus 20 comprises a chamber 22 having a wall structure 24(e.g., top, bottom sides, and ends). The chamber has an interior 26generally bounded by an interior surface 28 of the wall structure. Atemperature control system 30 may control the temperature of theinterior surface for purposes such as causing or preventing condensationof solvent vapor. As is discussed below, the solvent renders thefugitive porosity former sticky to adhere the other powders thereto.Thus, depending on implementation, the system 30 may serve as or be aheater, cooler, or both. Exemplary systems 30 are thermoelectricsystems, vapor compression systems (having a heat exchanger integratedwith the wall structure), or resistance or other heaters.

The apparatus 20 includes several sources of the constituent powders. Inan example of a metallic matrix-forming powder and a polymeric fugitiveporosity forming powder (fugitive powder), a source 40 may providemetallic powder 41 (e.g., a Cu—Ni alloy (e.g., Cu26Ni8.5Al4Cr) or anMCrAlY (although the Y may be eliminated in lower temperature enginelocations) and a source 42 may provide the fugitive powder 43 (e.g.,polymethyl methacrylate (PMMA)). The sources may comprise a reservoir44, 46 of the respective powders and a feed mechanism 48, 50. Exemplaryfeed mechanisms are spray feed mechanisms using a carrier gas from acarrier gas source 52, 54 (although shown separately, the carrier gassources may at least partially overlap such as using one or more gascylinders in common) and discharging respective sprays 53, 55 throughrespective nozzles 56, 58. As is discussed below, the spray dischargeproduces mixing of the powders. Exemplary carrier gas is nitrogen.Nitrogen (or an inert carrier gas) serves to limit oxygen when usingflammable solvent. If using water solvent (e.g., with PVA fugitiveparticles), air may be used.

To form agglomerates, the atmosphere within the chamber contains vaporsof a solvent for the fugitive powder. The vapors may be provided by avaporizer 60 within or communicating with the chamber interior. Thevaporizer may comprise a reservoir or other body of solvent 62 and aheater 64 (e.g., resistive) for heating and vaporizing the solvent.Another vaporizer example uses the bottom of the chamber as thevaporizer (e.g., a heated pool of solvent along the bottom). As thespray 55 passes through the solvent vapor, its particles pick up solventand become sticky to clump with the particles of the spray 53. Aconveyor 70 passes the mixed particles downstream along a main flowpathfor further processing such as solvent removal and classification(discussed below).

The atmosphere in the chamber may be up to 100% solvent vapor (in whichcase the temperatures will all be related to the boiling point of thesolvent (at atmospheric pressure)). In practice, the atmosphere willhave some other gases. These gases would include the carrier gas(es)plus any other gases which may come in via the powder introduction, plusleakage, residual air, outgassing, and the like. Such gases give theatmosphere some reduced vapor pressure (fraction) of the solvent.

To the extent that the atmosphere is <100% solvent, then the temperatureof condensation (dew point) will be reduced. Exemplary solvent vaporpartial pressure is at least 50% of the chamber atmosphere or at least75% or at least 90%.

The exemplary conveyor 70 is a vibratory conveyor having a bed 72 and avibration mechanism 74 (e.g., motor-driven, piezoelectric, pneumatic, orthe like. The exemplary conveyor uses a metallic powder to protect thebed 72. A source 80 provides this metallic powder 81 and may include areservoir 82 and a feed mechanism 84 an exemplary feed mechanism is afeedscrew or other non-spray system, although spray systems arealternatives. The powders 41 and 81 may be the same, or they may be thesame alloy but differing in morphology due to feedback issues (discussedbelow) or preprocessing of the powder 41 (discussed below) or may bemore fundamentally different such as differing alloys or differing size.In one differing size example, the particles of the powder 81 may bevery large such that they do not pass through a classifier and getrecycled back to the source 80 (perhaps with some of the fugitive powder43 and alloy powder 41).

In this example, a flowpath 500 extends downstream from the source 80.The flowpath extends along the bed 72. The alloy powder 81 forms a baselayer 88 atop the bed 72 and the alloy powder 41 is sprayed atop thebase layer along a footprint 90. The footprint 90 at least partiallyoverlaps with a footprint 92 of the spray 55 of the fugitive powder 43.In the illustrated example, the footprint 90 leads the footprint 92(i.e., the upstream extreme of the footprint 90 is upstream of theupstream extreme of the footprint 92). This means the powder 43generally lands atop the powder 41. In the exemplary embodiment, thedownstream (along the flowpath) extreme of the footprint 90 isdownstream of the downstream extreme of the footprint 92. This may helpfully embed the fugitive powder 43 in the alloy powder 41. Nevertheless,particular morphologies of final feedstock may be obtained by varyingthe footprints as well as the particle sizes and flow rates of theconstituent powders.

The vibratory conveyor 70 may cause some portion of the powder 81 to mixwith the other powders in the final spray feedstock. For this reason,the chemistry and particle size of the powder 81 may be chosen for itsrole in the ultimate spray feedstock. At its simplest, thisconsideration suggests using the same particle size and chemistry as forthe powder 41.

In another example, there is no separate source 80. Instead, the source40 may have a relatively larger footprint 90 extending further upstreamof the footprint 92.

As noted above, the mixed powders pass along the flowpath for furtherprocessing. FIG. 1A shows further details of a processing system 120.The flowpath leads to one or more collectors 122. FIG. 1A shows anexemplary pair of collectors which may selectively receive powderpassing along the flowpath (e.g., via a diverter such as amanually-controlled or actuator-driven flapper 124). The exemplaryflowpath thus has respective branches through the respective collectors.Along the branches, the collectors each have an upstream isolation valve126 and a downstream isolation valve 128 (e.g., pinch valves alongtubing).

The exemplary collectors 122 also serve to remove the solvent. While onecollector is open to the flowpath and receiving powder, the other isclosed to the flowpath and doing solvent removal. The exemplarycollectors have heating jackets 130 (e.g., resistive) or other heatingelements for heating the powder to vaporize the solvent. A vacuum andcondenser unit 140 (e.g., having a vacuum pump and a condensing heatexchanger (e.g., refrigerated or merely exchanging to ambientconditions)) draws the solvent vapor off. After solvent removal from agiven collector, its downstream isolation valve 128 may be opened todischarge the de-solvented powder for further processing. Afterdischarge, the downstream isolation valve 128 may then be closed and theupstream isolation valve opened to receive a subsequent charge ofpowder.

In the exemplary system, the flowpath branches reunite downstream of thedownstream isolation valves 128 and the flowpath proceeds to aclassifier 150. The exemplary classifier is a two-stage classifier withfeedback. Each stage may comprise a screen or other foraminate medium.The first stage medium 152 splits a flow 154 of over-size particles froma remainder flow 156 which passes to the second stage. In the exemplaryembodiment, the flow 154 passes to a crusher (e.g., rolling mill) 158whose output flow 160 is fed back along an oversize particle flowpath tothe first stage. The second stage medium 162 separates a flow 164 ofacceptable size particles and passes a flow 166 of under-size particles.The flow 164 may pass to a hopper 168 and then to packaging anddistribution for use as a spray feedstock.

The flow 166 may pass back along a return flowpath 520 from theclassifier to the first flowpath. The return flowpath may pass to one orboth of the sources 40 and 80 (e.g., directly merging with the flowpath500 at the source 80 or directly merging with a second flowpath at thesource 40 which in turns merges with the flowpath 500). The particularone may depend on a number of factors (e.g., degree of agglomeration,size and composition of the powders 41 and 81). Thus, this feedback orreturn flow 166 may account for some of the difference between thesources 40 and 80 even if the majority of powder in each is coming asidentical fresh powder. If the bed powder (alloy powder 81) is sized todifferentiate it from the agglomerates and source powders 41 and 43(e.g., is larger than the agglomerates), it may require additionalsegregation for reuse (e.g., an additional coarse stage before thoseshown).

Temperature management of the respective powder sources may play a rolein achieving desired final powder properties. Due to its introductionupstream along the conveyor 70, the alloy powder 81 may be referred toas a first powder. As noted above, the first powder (if included) mayserve to protect the conveyor bed 72 surface. The first powder may beheated (e.g., by a heater 170 such as a resistive heating jacket (FIG.1)) to a point where the vapor will not condense on it. This heating maybe just to or above the boiling point or dew point of the solvent (e.g.,by 5-15° F. (2.8-8.3° C.) above dew point), but slightly higher may helplimit clumping of the agglomerates together by boiling off some or allof the solvent that arrives with the powders landing on it from thesprays 53 and 55.

Another exemplary heater 170 is a vapor jacket with controlled pressure(temperature for condensation of the vapor is proportional to thepressure (partial pressure of the vapor)). If the solvent vapor is usedin the vapor jacket, then small adjustment from atmospheric pressurewill result in temperature that is just above or below the dew point ofthe pure vapor at atmospheric pressure (thus, one may have precisecontrol).

The alloy powder 41 forms a second powder at a temperature that may beselected to control condensation (e.g., less than dew point, such as aroom temperature powder introduced to a 100° F. (38° C.) chamber).Control to this temperature may be a heating or a cooling/chillingjacket 172 (e.g., via a heat pump system 182). Cooling would allow theintroduction of more solvent which may be desirable in some situations.

The fugitive powder is cooled (e.g., via a heat exchanger 174 associatedwith a pump system 184). This may be to a temperature of 0° C. (32° F.).This induces condensation of solvent on the fugitive powder spray. Thistemperature may be less than that of the metallic powder due to lowerheat capacity of the fugitive and/or a desire to get a highercondensation directly on the fugitive than directly on the alloy powder.

If a nonmetallic filler (e.g., solid lubricant such as hBN or analternative non-lubricant for coating friability/abradability, e.g., oneor more oxides such as a metal oxide and/or rare earth oxide) is to beintroduced there are a number of options. Some options involvepreblending the nonmetallic filler with the alloy powder of the source40 (and/or source 80 if present). Other options involve a source (notshown) similar to the sources 40 and 42 containing the filler. Forexample, this source may have a spray footprint larger than thefootprint 92 (e.g., coextensive with the footprint 90).

The use of “first”, “second”, and the like in the following claims isfor differentiation within the claim only and does not necessarilyindicate relative or absolute importance or temporal order. Similarly,the identification in a claim of one element as “first” (or the like)does not preclude such “first” element from identifying an element thatis referred to as “second” (or the like) in another claim or in thedescription.

Where a measure is given in English units followed by a parentheticalcontaining SI or other units, the parenthetical's units are a conversionand should not imply a degree of precision not found in the Englishunits.

One or more embodiments have been described. Nevertheless, it will beunderstood that various modifications may be made. For example, whenapplied to an existing baseline process, details of such baseline mayinfluence details of particular implementations. Accordingly, otherembodiments are within the scope of the following claims.

What is claimed is:
 1. An apparatus for manufacturing a powder, theapparatus comprising: a chamber; a temperature control system for thechamber interior; a conveyor within the chamber; a first powder sourcewithin or coupled to the chamber and configured to supply a first powderto a first powder flowpath; said first powder flowpath passing as fromthe first powder source through the chamber and passing along theconveyor; a second powder source within or coupled to the chamber andconfigured to supply a second powder to a second powder flowpath; saidsecond powder flowpath passing from the second powder source and mergingwith the first powder flowpath along the conveyor; a third powder sourcewithin or coupled to the chamber and configured to supply a third powderto a third powder flowpath; said a third powder flowpath passing fromthe third powder source and merging with the first powder flowpath alongthe conveyor; and a vaporizer within the chamber or coupled thereto todeliver vaporized liquid solvent to the second powder powder along thesecond powder flowpath and the third along the third powder flowpath inthe chamber.
 2. The apparatus of claim 1 further comprising: aclassifier; and a return flowpath from the classifier to the firstflowpath.
 3. The apparatus of claim 2 wherein: the classifier is atwo-stage classifier with the first stage having an over-size particleflowpath passing back through a crusher.
 4. The apparatus of claim 2further comprising upstream of the classifier: first and secondcollectors having heating elements for heating agglomerated powder tovaporize the solvent; and a vacuum and condenser unit for drawing offsolvent vapor.
 5. The apparatus of claim 2 further comprising for eachof the first and second collectors: upstream of the first and secondcollectors, an upstream isolation valve; and upstream of the classifierand downstream of the first and second collectors, a downstreamisolation valve opened to receive a subsequent charge of powder.
 6. Theapparatus of claim 2 wherein the conveyor is a vibratory conveyor. 7.The apparatus of claim 1 wherein the conveyor is a vibratory conveyor.8. The apparatus of claim 1 wherein the temperature control systemcomprises: a heater.
 9. The apparatus of claim 1 wherein: the firstpowder source is a source of a first metallic powder; the second powdersource is a source of a second metallic powder; and the third powdersource is a source of a polymeric powder.
 10. The apparatus of claim 9wherein: the first metallic powder and the second metallic powder are ofalloys of the same composition.
 11. The apparatus of claim 1 wherein thesecond powder source has: a heat pump system for cooling the secondpowder.
 12. The apparatus of claim 1 wherein the third powder sourcehas: a heat pump system for cooling the third powder.
 13. The apparatusof claim 1 wherein: the liquid solvent comprises acetone.
 14. Anapparatus for manufacturing an agglomerate powder, the apparatuscomprising: a chamber; a temperature control system for the chamberinterior; a conveyor within the chamber; a first powder source of afirst powder within or coupled to the chamber; a first powder flowpathfrom the first powder source through the chamber and passing along theconveyor; a second powder source of a second powder within or coupled tothe chamber; a second powder flowpath from the second powder sourcemerging with the first powder flowpath along the conveyor; a thirdpowder source of a third powder within or coupled to the chamber; athird powder flowpath from the third powder source merging with thefirst powder flowpath along the conveyor; and a vaporizer within thechamber or coupled thereto to deliver vaporized liquid solvent to thesecond powder along the second powder flowpath and the third powderalong the third powder flowpath in the chamber for agglomerating thesecond and third powders for forming the agglomerate powder.
 15. Theapparatus of claim 14 further comprising: a classifier; and a returnflowpath from the classifier to the first flowpath.
 16. The apparatus ofclaim 14 wherein the second powder source has: a heat pump system forcooling the second powder.
 17. The apparatus of claim 16 wherein thethird powder source has: a heat pump system for cooling the thirdpowder.
 18. The apparatus of claim 14 wherein the third powder sourcehas: a heat pump system for cooling the third powder.
 19. An apparatusfor manufacturing a powder, the apparatus comprising: a chamber; atemperature control system for the chamber interior; a conveyor withinthe chamber; a first powder source within or coupled to the chamber; afirst powder flowpath from the first powder source through the chamberand passing along the conveyor; a second powder source within or coupledto the chamber and including means for cooling the second powder; asecond powder flowpath from the second powder source merging with thefirst powder flowpath along the conveyor; a third powder source withinor coupled to the chamber and including means for cooling the thirdpowder; a third powder flowpath from the third powder source mergingwith the first powder flowpath along the conveyor; and a vaporizerwithin the chamber or coupled thereto to deliver vaporized liquid to thechamber for condensing on at least one of the second powder and thethird powder to agglomerate the first, second, and third powders into anagglomerate powder.
 20. The apparatus of claim 19 further comprising: aclassifier; and a return flowpath from the classifier to the firstflowpath.